1. Field of the Invention
The invention relates to a change-out handle system for the releasable coupling of two elongated, axially relatively displaceable functional parts to a medical instrument unit that is couplable thereto and to a corresponding medical instrument.
2. Description of the Related Art
In the area of medical technology there are on occasions medical instruments which include two elongated, axially relatively displaceable functional parts, in particular for endoscopy applications. Important examples, among others, are stone catcher instruments with a wire basket that can be folded out to capture stones and the like in tissue cavities, wire filter instruments and guide wire units for catheter instruments. The two elongated, axially relatively displaceable functional parts can be, for example, a so-called wire pull and a tube, i.e. sheath, surrounding said wire pull.
The axial relative displacement of the two functional parts controls a distal functional element into at least two different functional states, in the case of a stone catcher instrument, for example, a distal wire basket is optionally controlled into a collapsed state retracted into the tube or into a folded-out state pushed forward out of the tube. At the proximal end, the two functional parts are typically coupled to a control handle in such a manner that the tube is connected to a stationary handle portion and the wire pull is connected to a handle portion that is to be actively manipulated. In the case of these types of conventional arrangements, once the instrument has been inserted into a body tissue canal, the tube consequently remains stationary with respect to said canal, whilst the wire pull is moved axially forward and backward by the proximal user manipulation in order, for example, to move a stone catcher basket distally out of the tube and to fold it open and after catching a stone, to move it back until it is secured. The wire basket consequently changes its axial position in the tissue canal during this functional movement, which can be undesirable or can make the stone catching function more difficult. Conventional handle systems for such applications also frequently have the problem that releasing the functional parts from the handle is often not possible or only possible with difficulty or is only possible when using loose connecting parts that may be lost and/or particular tools.
US disclosure document 2005/0113862 A1 discloses a handle system for releasably coupling two elongated, axially relatively displaceable functional parts of a medical instrument, in particular a guide wire unit, in the form of a central wire pull and a tube surrounding said wire pull, which has a deformable portion between its distal and its proximal end and between said deformable portion and the proximal end has a resiliently prestressing portion, through the prestressing force of which the axial length of the deformable portion can be modified. The wire pull and the tube are in each case fixedly connected to each other at the distal and at the proximal end. A handle with a front and a rear handle part can be used for manipulation, wherein the front handle part has an opening, through which the wire pull and the tube surrounding said wire pull are guided by way of a proximal end portion, which includes the resiliently prestressing portion. In this case, the proximal end portion of the wire pull and the tube are received loosely in an axial receiving bore of the rear handle part, and the tube portion connecting distally to the resiliently prestressing portion is releasably fixed on the front handle part by means of a screw clip. The two handle parts are guided together in an axially relatively displaceable manner for a predetermined length. Through the action of the resiliently prestressing portion, the deformable tube portion is held in a first form state. By manipulating the rear handle part, the deformable tube portion is moved out of said first into a second form state. In this case, the first form state serves to anchor the guide wire unit in a tissue canal in order, for example, to be able to push on and insert a catheter tube via the guide wire unit, whilst the second form state represents an insertion state, in which the guide wire unit can be moved into a tissue canal or out of said tissue canal again.
It is an object of the invention is to provide a change-out handle system of the aforementioned type, which enables a comparatively simple, functionally reliable, releasable coupling of the functional parts to the handle parts, an associated medical instrument unit and an associated medical instrument.